Behavioral adaptations of bees for pollen collecting from Cassia flowers

Abstract

Among the plants which have tubular anthers with apical pores is Cassia biflora, a very cormon weedy shrub in the Guanacaste region, Costa Rica. In order to collect pollen from these flowers bees have adopted quite different techniques of pollen collecting. One is by means of vibratíons which produce peculiar intermittent buzúng sounds and cause the pollen to shoot out of the anther. Another technique is making small holes with the mandibles on the tubular anthers and then collecting the pollen through these holes with the aid of the proboscis.The pollen is then lodged on the thoracic sternum from which it is transferred to the corbicula (bees observed using this method were stingless bees of the subgenus Trigona). The transfer of pollen from the sternum to the hind legs is accomplished while the bee hovers, as if suspended at one point in the air. A third technique observed, used by the honey bee and certain species of stingless bees, consists merely in picking up the pollen grains left on the corolla and anthers by the other bees, sometimes utilizing the holes already made on the anthers by biting bees.